Your main leader and your three-page briefing on the revival of nuclear power around the globe, and especially in America, are appropriately cautious (“Nuclear Power’s New Age” and “Atomic Renaissance,” September 8, 2007). Climate change is giving it a new lease of life, but formidable issues remain. The onus is now on the builders, operators, and regulators of nuclear power, who must demonstrate to all concerned that they are offering solutions to a host of problems with the old nuclear technology and its management. It appears that much has been achieved in the last few decades, but the problem of nuclear-waste disposal remains a grave one. As you point out in your briefing, reliable long-term disposal is not yet available anywhere. The cost of protecting untold future generations from radiation must be factored into the nuclear-power equation. And it is likely to overshadow all the other life-cycle costs by a factor of two or three. This may yet prove to be the Achilles’ heel of nuclear power.